Customize Mender

This chapter assumes that you are familiar with rootfs overlays.

Mender Server address

For self-managed installations of the Mender server (not hosted Mender, you will need to provide a custom server address in the converted image. To do so, generate a new overlay using the bootstrap-rootfs-overlay-production-server.sh script, and give the --server-url argument:

./scripts/bootstrap-rootfs-overlay-production-server.sh \
    --output-dir ${PWD}/rootfs_overlay_production \
    --server-url https://my-mender-server.com/

It is also possible to override the public certificate that Mender will use to authenticate the server. To do so, add the --server-cert and a path to the certificate to the command above. This is not necessary if you are using a certificate which has been signed by a public Certificate Authority (CA).

Configuration file

To provide a custom mender.conf configuration file inside the image, put the configuration file in the /etc/mender directory inside your own overlay directory. Use these commands to create an overlay and put a custom configuration file inside the overlay:

mkdir -p rootfs_overlay_production/etc/mender
cat > rootfs_overlay_production/etc/mender/mender.conf <<EOF
{
  "ServerURL": "https://my-server.com/"
}
EOF
chmod 600 rootfs_overlay_production/etc/mender/mender.conf
sudo chown root:root rootfs_overlay_production

The options inside the JSON structure can be any option from the client configuration options.

Identity

To add your own identity script to the image, execute these commands:

SCRIPT=<PATH-TO-IDENTITY-SCRIPT>
mkdir -p rootfs_overlay_production/usr/share/mender/identity
cp $SCRIPT rootfs_overlay_production/usr/share/mender/identity/
chmod 755 rootfs_overlay_production/usr/share/mender/identity/*
sudo chown root:root rootfs_overlay_production

Replace <PATH-TO-IDENTITY-SCRIPT> with the path to your identity script. Remember that the name of the script must be mender-device-identity, while the path can be arbitrary. To learn more about how to write identity scripts, see the Identity section.

Inventory

To add your own inventory script to the image, execute these commands:

SCRIPT=<PATH-TO-INVENTORY-SCRIPT>
mkdir -p rootfs_overlay_production/usr/share/mender/inventory
cp $SCRIPT rootfs_overlay_production/usr/share/mender/inventory/
chmod 755 rootfs_overlay_production/usr/share/mender/inventory/*
sudo chown root:root rootfs_overlay_production

Replace <PATH-TO-INVENTORY-SCRIPT> with the path to your inventory script. Remember that the name of the script must start with mender-inventory-, while the path can be arbitrary. To learn more about how to write inventory scripts, see the Inventory section.

Update Modules

To install an Update Module in the image, execute these commands:

MODULE=<PATH-TO-UPDATE-MODULE>
mkdir -p rootfs_overlay_production/usr/share/mender/modules/v3
cp $MODULE rootfs_overlay_production/usr/share/mender/modules/v3/
chmod 755 rootfs_overlay_production/usr/share/mender/modules/v3/*
sudo chown root:root rootfs_overlay_production

Replace <PATH-TO-UPDATE-MODULE> with the path to your Update Module. To learn more about Update Modules, visit the section "Use an Update Module".